Screen printing procedures utilize a series of screens each coated with an emulsion that is selectively exposed to present a pattern through which ink may flow for application to a substrate such as a fabric or paper. The screens are prepared by coating a photosensitive emulsion onto a screen mesh and subsequently drying the emulsion. An artwork pattern is applied to the screen which is then exposed to a light spectrum which causes curing and hardening of that portion of the emulsion that is exposed. Washing of the uncured emulsion from the area of the screen shielded by the pattern to be reproduced provides a printing stencil. A series of stencils providing different colors to the overall pattern are then successively positioned in the printing device over the substrate and used to apply appropriately colored ink to the appropriate portions of the substrate.
To ensure proper location of the successive screens over the substrate, a variety of registration devices have been proposed in the prior art. Many of these involve the use of complex and costly mechanical equipment (see, for example, U.S. Pat. Nos. 5,063,842, issued on Nov. 12, 1991, and 5,226,362, issued on Jul. 13, 1993). Another proposal has been to utilize automatically controlled positioning devices to register the screens with a light source (see U.S. Pat. No. 5,241,187, issued Aug. 31, 1993). Yet another method of registration has been to use a series of pegs and clamps to assure alignment (see, for example, U.S. Pat. No. 5,226,366, issued Jul. 13, 1993; U.S. Pat. No. 5,094,160, issued Mar. 10, 1992; and U.S. Pat. No. 5,127,321, issued Jul. 7, 1992.
While the foregoing systems have performed satisfactorily in their respective environments, a need has continued to exist for a simple, efficient and economical registration system that is suitable for printing shops and jobs without requiring a high initial investment as is required by the above-noted prior art.